This is the major part of the interface that shows the content of the downloaded image. All changes made to the image are shown in this area straight away.

You can use the button “Compare with original” that allows viewing the original image and the image after last changes for their comparison.
Compare with original.

When pressing the button you will see the image downloaded originally without deleting the current image and when you release the button you will see your current image in the “Image viewing area”. The current image is your original image after application of various filters and effects.